This invention relates generally to a manually actuated pump sprayer having a means which prevents clogging of the discharge orifice due to product drying at the orifice.
Prior art pumps of the general type as aforedescribed are known as having some type of anti-clog means such as the provision of a small projection extending into the orifice opening from outside the orifice cup. The projection is provided on a cover overlying the plunger head and shiftable relatively thereto for both sealing the orifice closed and for breaking away any accumulated dried product which may have accumulated on the outside surface of the orifice cup. U.S. Pat. Nos. 5,207,785 and 5,105,988 are examples of such prior art.
U.S. Pat. No. 5,785,208 likewise discloses a manual pump sprayer having an overcap on the plunger head shiftable relatively thereto, a projection on the overcap extending into the orifice at the outer surface of the orifice cup, and a suck-back feature being provided for suctioning any product away from the orifice to avoid clogging.
These solutions to prevent orifice clogging are not, however, without their disadvantages. For example, extending a protrusion or the like into the orifice from the outer surface of the orifice cup for anti-clogging purposes, could over time distort the orifice and thereby adversely affect the quality of spray through the orifice. Also the protrusion on the overcap could after repeated use overshoot or undershoot the orifice in the non-use position such that the protrusion is out of axial alignment with the orifice in a non-use position thereby defeating the anti-clog feature.
U.S. Pat. Nos. 3,680,738 and 3,351,247 each disclose sealing of the discharge passage or orifice of a dispenser in a non-use position, the discharge passage reciprocating relative to a stationary wall surrounding the plunger having an opening with which the orifice is axially aligned when plunged. However, each such dispenser has but a single plunger return spring rendering it more difficult to control the alignment between the orifice and the fixed cover opening. Also a seal bead or a ring at the orifice becomes abraded after repeated use as it scrapes along the inner edge of the orifice formed in the fixed wall during each plunger reciprocation. Such abrasion adversely affects the seal function.